Messages in this thread | | | From | Xiaoming Ni <> | Subject | [PATCH v3 0/3] kernel/notifier.c: avoid duplicate registration | Date | Wed, 10 Jul 2019 11:09:07 +0800 |
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Registering the same notifier to a hook repeatedly can cause the hook list to form a ring or lose other members of the list.
case1: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2);
case2: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_call_chain(&test_notifier_list, 0, NULL);
case3: lose other hook test2 atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2); atomic_notifier_chain_register(&test_notifier_list, &test1);
case4: Unregister returns 0, but the hook is still in the linked list, and it is not really registered. If you call notifier_call_chain after ko is unloaded, it will trigger oops. if the system is configured with softlockup_panic and the same hook is repeatedly registered on the panic_notifier_list, it will cause a loop panic.
so. need add a check in in notifier_chain_register() to avoid duplicate registration
v1: * use notifier_chain_cond_register replace notifier_chain_register
v2: * Add a check in notifier_chain_register() to avoid duplicate registration * remove notifier_chain_cond_register() to avoid duplicate code * remove blocking_notifier_chain_cond_register() to avoid duplicate code
v3: * Add a cover letter.
Xiaoming Ni (3): kernel/notifier.c: avoid duplicate registration kernel/notifier.c: remove notifier_chain_cond_register() kernel/notifier.c: remove blocking_notifier_chain_cond_register()
include/linux/notifier.h | 4 ---- kernel/notifier.c | 41 +++-------------------------------------- net/sunrpc/rpc_pipe.c | 2 +- 3 files changed, 4 insertions(+), 43 deletions(-)
-- 1.8.5.6
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